Effects of Leucaena pallida and Sesbania sesban supplementation on testicular histology of tropical sheep and goats

Thirty Ethiopian highland rams with an average body weight of 23.7kg (S.D.=1.23) and age of 18 months and 25 East African bucks with an average body weight of 18.6kg (S.D.=2.06) and age of 14 months were used to study the long term effects of supplementation with the leaves of Leucaena pallida and Sesbania sesban on testicular histology. Within species, animals were blocked based on body weight and scrotal circumference and randomly assigned, within blocks, to five nutritional treatment groups in a complete randomised block design. All animals were provided with unchopped teff (Eragrostis tef) straw ad libitum and were supplemented with either 150g of wheat bran (control), leucaena (200 or 400g) or sesbania (200 or 400g) leaves for a period of 6 months. At the end of the experimental period, all animals were surgically castrated and testicular samples were collected and prepared for histopathological examination. In sheep 200g S. sesban induced relatively more necrosis of the seminiferous tubules than 200g L. pallida, but with similar degree of tubular degeneration. However, lesions in testis of goats fed on 200g S. sesban and 200g L. pallida did not differ. The effect of 400g S. sesban and 400g L. pallida in sheep indicated that the former hardly induced lesions except depressive effect on spermatogenesis. Similar results were observed in goats. About 400g S. sesban induced milder lesions in sheep and goats than were 200g S. sesban. The lesions were compared and discussed in relation to the phytochemical composition of the supplementary feeds.     

The antidepressant-like effect of Ocimum basilicum in an animal model of depression

We investigated the efficacy of Ocimum basilicum (OB) essential oils for treating depression related behavioral, biochemical and histopathological changes caused by exposure to chronic unpredictable mild stress (CUMS) in mice and to explore the mechanism underlying the pathology. Male albino mice were divided into four groups: controls; CUMS; CUMS plus fluoxetine, the antidepressant administered for pharmacological validation of OB; and CUMS plus OB. Behavioral tests included the forced swim test (FST), elevated plus-maze (EPM) and the open ?eld test (OFT); these tests were performed at the end of the experiment. We assessed serum corticosterone level, protein, gene and immunoexpression of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) as well as immunoexpression of glial fibrillary acidic protein (GFAP), Ki67, caspase-3 in the hippocampus. CUMS caused depression in the mice as evidenced by prolonged immobility in the FST, prolonged time spent in the open arms during the EPM test and reduction of open field activity in the OFT. OB ameliorated the CUMS induced depressive status. OB significantly reduced the corticosterone level and up-regulated protein and gene expressions of BDNF and GR. OB reduced CUMS induced hippocampal neuron atrophy and apoptosis, and increased the number of the astrocytes and new nerve cells. OB significantly increased GFAP-positive cells as well as BDNF and GR immunoexpression in the hippocampus.     

Productivity of forests in the Eurosiberian boreal region and their potential to act as a carbon sink –- a synthesis

Based on review and original data, this synthesis investigates carbon pools and fluxes of Siberian and European forests (600 and 300 million ha, respectively). We examine the productivity of ecosystems, expressed as positive rate when the amount of carbon in the ecosystem increases, while (following micrometeorological convention) downward fluxes from the atmosphere to the vegetation (NEE = Net Ecosystem Exchange) are expressed as negative numbers. Productivity parameters are Net Primary Productivity (NPP=whole plant growth), Net Ecosystem Productivity (NEP = CO₂ assimilation minus ecosystem respiration), and Net Biome Productivity (NBP = NEP minus carbon losses through disturbances bypassing respiration, e.g. by fire and logging). Based on chronosequence studies and national forestry statistics we estimate a low average NPP for boreal forests in Siberia: 123 gC m^–2 y^–1. This contrasts with a similar calculation for Europe which suggests a much higher average NPP of 460 gC m^–2 y^–1 for the forests there. Despite a smaller area, European forests have a higher total NPP than Siberia (1.2–1.6 vs. 0.6–0.9 × 10¹⁵ gC region^–1 y^–1). This arises as a consequence of differences in growing season length, climate and nutrition. For a chronosequence of Pinus sylvestris stands studied in central Siberia during summer, NEE was most negative in a 67-y old stand regenerating after fire (– 192 mmol m^–2 d^–1) which is close to NEE in a cultivated forest of Germany (– 210 mmol m^–2 d^–1). Considerable net ecosystem CO₂-uptake was also measured in Siberia in 200- and 215-y old stands (NEE:174 and – 63 mmol m^–2 d^–1) while NEP of 7- and 13-y old logging areas were close to the ecosystem compensation point. Two Siberian bogs and a bog in European Russia were also significant carbon sinks (– 102 to – 104 mmol m^–2 d^–1). Integrated over a growing season (June to September) we measured a total growing season NEE of – 14 mol m^–2 summer^–1 (– 168 gC m^–2 summer^–1) in a 200-y Siberian pine stand and – 5 mol m^–2 summer^–1 (– 60 gC m^–2 summer^–1) in Siberian and European Russian bogs. By contrast, over the same period, a spruce forest in European Russia was a carbon source to the atmosphere of (NEE: + 7 mol m^–2 summer^–1 = + 84 gC m^–2 summer^–1). Two years after a windthrow in European Russia, with all trees being uplifted and few successional species, lost 16 mol C m^–2 to the atmosphere over a 3-month in summer, compared to the cumulative NEE over a growing season in a German forest of – 15.5 mol m^–2 summer^–1 (– 186 gC m^–2 summer^–1; European flux network annual averaged – 205 gC m^–2 y^–1). Differences in CO₂-exchange rates coincided with differences in the Bowen ratio, with logging areas partitioning most incoming radiation into sensible heat whereas bogs partitioned most into evaporation (latent heat). Effects of these different surface energy exchanges on local climate (convective storms and fires) and comparisons with the Canadian BOREAS experiment are discussed. Following a classification of disturbances and their effects on ecosystem carbon balances, fire and logging are discussed as the main processes causing carbon losses that bypass heterotrophic respiration in Siberia. Following two approaches, NBP was estimated to be only about 13–16 mmol m^–2 y^–1 for Siberia. It may reach 67 mmol m^–2 y^–1 in North America, and about 140–400 mmol m^–2 y^–1 in Scandinavia. We conclude that fire speeds up the carbon cycle, but that it results also in long-term carbon sequestration by charcoal formation. For at least 14 years after logging, regrowth forests remain net sources of CO₂ to the atmosphere. This has important implications regarding the effects of Siberian forest management on atmospheric concentrations. For many years after logging has taken place, regrowth forests remain weaker sinks for atmospheric CO₂ than are nearby old-growth forests.     

Using wintergreen oil for mounting mosquito larvae: a safer alternative to xylene

Permanent mounting of fourth instar mosquito larvae is essential for identifying Aedes spp. This procedure requires extensive exposure to xylene, a clearing agent in the mounting process. We investigated wintergreen oil as a substitute for xylene. Five hundred larvae were mounted on slides to evaluate shrinkage or expansion of specimens after clearing using xylene or wintergreen oil. We examined the ventral brush and siphonal hair tufts for species identification and for preservation of morphological characteristics after clearing specimens in xylene or wintergreen oil. Shrinkage of the length of whole larvae and width of the head, thorax and abdomen after mounting was significantly greater after clearing with xylene than with wintergreen oil. The length of the comb scale nearest the ventral brush was similar for both clearing agents. The clarity of the specimens after mounting was improved by clearing with wintergreen oil, but the integrity of the ventral brush and siphonal hair tufts were similar for both clearing agents.     

Evaluation of corn gluten meal with urea as a source of supplementary nitrogen for growing calves and lambs

Three growth trials and a metabolism study were conducted to evaluate corn gluten meal—urea (CGM—urea) combinations compared to a urea control as sources of supplementary nitrogen for growing calves and lambs fed on diets based on corn cobs.In the first growth study cattle were fed individually twice daily while in the sheep growth study and the second cattle growth study, animals were fed in groups. The average daily gain and feed conversion were similar for animals given the soya bean meal (SBM) and CGM—urea supplements. Feed intakes were similar for all treatments except for growth study 1. Nitrogen retention and dry matter and protein digestibility did not differ significantly between the SBM and CGM—urea supplemented groups. Urea consistently gave inferior results in all the experiments. These results suggest that CGM—urea combination is essentially equal to SBM in supporting growth of calves and lambs.     

Reproductive performance of the Y'ankasa sheep of Nigeria

The reproductive performance of the Y'ankasa sheep of Nigeria was studied to determine any seasonal effects on their breeding pattern. The study also aimed at documenting the reproductive performance levels of these animals as a basis for evaluating the results of any breeding improvement program in Nigeria using indigenous or exotic breeds of sheep. The study shows that this breed of sheep is a year-round breeder although some months favor lambing more than others. The age at first lambing and the lambing interval for these animals are 15.5 months and 9.7 months respectively. For 1975, the conception and lambing rates were 87.8% and 139% respectively. The rates for 1976 were 91% and 148%. Seventy-seven percent of the lambing were singles and the rest twins. The sex ratio, number of females per 100 lambs, was 49%. Lamb mortality rate up to 3 months of age was 12.0%. The lambs in our study grew very slowly, gaining only 15 kg in a 9-month period. By 10 months of age these lambs wieghed only 20 kg.     

Genetic and phenotypic differences between thistle populations in response to habitat and weed management practices

Rapid evolutionary change is increasingly being recognized as commonplace, but the evolutionary consequences for species and ecosystems under human‐induced selection regimes have not been explored in detail, although many species occur in such environments. In a common garden experiment and with amplified fragment length polymorphism markers, we examined whether genetic differentiation has taken place between spatially intermixed populations of creeping thistles Cirsium arvense (Asteraceae) collected from a natural habitat (maritime shores), a semi‐natural habitat (road verges) and arable fields under two management regimes: conventional and organic farming. Populations of C. arvense have altered genetically and locally adapted their growth patterns with changed land use. Although plants from different habitats showed similar total biomass production, shoot and root production was higher for maritime populations, suggesting selection for increased competitive ability. Competitive ability then declined in the order semi‐natural, conventional farms and organic farms. Thistles in arable fields may be more selected for tolerance against disturbances from herbicides and mechanical weed control. In addition, early shoot sprouting and genetic analysis showed differentiation between plants originating from conventional farms and farms that were converted to organic 9–30 years ago, suggesting some adaptation to altered crop cultivation practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 797–807.     

Seasonal variations in water requirement and influence of intermittent watering on grazing Yankasa sheep

Eighty male Yankasa sheep were used in two different experiments. A set of forty sheep, divided into four groups of ten rams each, were used in each experiment. The animals weighed, on average, 20 kg and were 15 months old. The animals were selected from the sheep flock of the Ahmadu Bello University Farm. They were grazed for 6 h daily for a period of 50 days during which they were subjected to intermittent watering. Watering intervals were 24 h, 48 h, 72 h and 96 h for Treatments 1, 2, 3 and 4, respectively. The experiment was carried out during the wet season of June to August and repeated in the hot, dry season of March to April, using another set of 40 Yankasa male sheep to find seasonal variations. The animals were not allowed to drink on the field when grazing during the rainy season.Seasonal variations had significant (P < 0.05) effects on the water intake and weight gains of Yankasa sheep. The animals lost 18.8 g, 115.2 g and 172 g daily on 48 h, 72 h and 96 h watering intervals in the dry season, but, on daily watering, they gained 66 g. During the rainy season the animals gained 135.6 g, 124.4 g, 108 g and 92.2 g body weight daily under 24 h, 48 h, 72 h and 96 h watering intervals, respectively.Slight variations were noted in rectal temperatures between treatments with a range of 39.07°C–39.59°C for the dry season and 38.73°C–38.95°C for the wet season. Respiratory rate was significantly (P < 0.05) affected by watering intervals, especially during the dry season, with average values of 32.4, 25.8, 20.5 and 19.9 for 24 h, 48 h, 72 h and 96 h watering intervals. Jaw movements were reduced with long watering intervals, and also pulse rate, especially in the dry season.The results suggest that grazing Yankasa sheep do not have to be watered daily during the wet season but free drinking water is very essential, at least every 24 h (daily) during the dry season.